#hello_world_01
# print('Hello World')
# if 3 > 0 :
#     print('OK')
#     print('yes')
# x = 3
# y = 4
# print(x + y)
#print_02
# print('hello world')
# print('hello', 'world')
# print('hello' + 'world')
# print('hello', 'world',sep='***')
# print('#' * 50)
#base_03
# print(5/2)
# print(5//2)
# print(5 ** 3)
# print(5 > 3)
# print(20 > 15 > 10)
# print(not 20 > 10)
#input_04
# number = input('shuru')
# print(number)
# print(type(number))
# #print(number + 10) # err
# print(int(number) + 10)
# print(number + str(10))
#input_print_05
# username = input('username')
# print('welcome',username)
# print('welcome' + username)
#str_usr_base_06
# sen = 'tom\'s pet is a cat'
# sen = "tom's pet is a cat"
# sen = "tom said:\"hello world\""
# sen = 'tom said:"hello world"'
# words = '''
# hello
# world
# tom
# '''
# py_str = 'python'
# len(py_str)
# py_str[0]
# py_str[-1]
# py_str[2:4]
# py_str[2:]
# py_str[:2]
# py_str[1::2]
# py_str[::-1]
# py_str + 'is good'
# py_str * 3
# 't' in py_str
# 'th' in py_str
# 'to' in py_str
# 'to' in py_str
#list_base_07
# alist = [10, 20, 30, 'bob', 'alice', [1, 2, 3]]
# len(alist)
# alist[-1]
# alist[-1][-1]
# [1,2,3][-1]
# alist[-2][2]
# alist[3:5]
# 10 in alist
# 'o' in alist
# 100 not in alist
# alist[-1] = 100
# alist.append(200)
#tuple_base_08
# atuple = (10, 20, 30, 'bob', 'alice', [1,2,3])
# len(atuple)
# 10 in atuple
# atuple[2]
# atuple[3:5]
##atuple[-1] = 100    tuple   no
#dict_base_09
# adict = {'name': 'tom','age': 23}
# len(adict)
# 'bob' in adict #False
# 'name' in adict
# adict['email'] = 'bob@tedu.com'
# adict['age']  = 25
#judge_base_10
# if 3 > 0:
#     print('yes')
#     print('OK')
# if 10 in [10,20,30]
#     print('ok')
# if -0.0:
#     print('yes')
# if [1,2]:
#     print('yes')
# if '  ':
#     print('yes')   #  mei kong